Chris

Airwindows is one guy: me! I am an audio hacker and computer programmer from way back. I seek only to continue my life up here in Vermont, inventing things and putting them onto the internet, sometimes for free and sometimes for pay. My hope is that people richer than me (i.e. most people) don't rob me. My other hope is for another cup of Aeropress. One out of two ain't bad!

Much like my livestream on adding a Mudbucker to an electric bass, this video is about ways you can make custom drum mics using spare speaker parts, even if you’re not on a platinum seller budget! All about how a SubKick works, and a trick for getting DI beater click. Plus, these do not need a preamp to work! :)

In this video, I’m showing you how I made my ‘beater click’ and sub-kick ‘microphones’ and wired them. I’m assuming you either know how to wire things, or are willing to learn, and focussing much more on the specifics of how I’m implementing it. Because execution is everything with this stuff: placement of the tiny ‘subkick’ has a huge effect on its performance.

The beater click transducer is a piezo guitar pickup, probably a Fishman. In this context, any sort of piezo element ought to do. You mustn’t wire it parallel to the subkick or the low impedance will totally wipe out the piezo’s output (it’ll all go through the speaker, uselessly). An input with transformer balancing will also have this problem to a lesser extent. You can hear it all by itself in the video.

The subkick is a tiny acoustic suspension speaker where I cut away the basket with tin-snips: you can see in the video how I did it. I left some suspension to act as a sort of ‘hovercraft skirt’, helping to contain air near the drum-head. A larger driver might need support around the edges of the speaker, but this one is so tiny I could rely on the spider (suspension near the magnet) alone, without scraping. If it’s a driver this small, it must be acoustic suspension or the resonant frequency will be way too high! Removing the outer suspension also lowers the resonant frequency, which helps. When hacking apart a speaker be prepared for the possibility that you destroy the speaker: I’ve done this before, so I was pretty sure mine would be OK :) you can hear it wired up with the piezo in the video, it’s not all by itself.

I wired up the piezo, then did drum recordings with all mics, notably the normal kick mic (a modded 57 because it has to focus on mids in this scenario: it ends up as bass/mid/treble mics on the kick). I recorded with the piezo wired to the tip of the TRS jack, then flipped phase to see what was better. I liked the sound of inverted phase, so I rewired the piezo, connecting it to the ring of the TRS jack. That meant I could wire the speaker to the tip, giving me two independent inputs into the converter (one out-of-phase, being used for the piezo). I tried both polarities for the speaker and settled on my favorite: you can also wire up a phase switch on either of these, like you would on a guitar pickup.

Opening the video, and at the end, you can hear an example of all three ‘microphones’ mixed together, with the 57 padded down to not dominate the weirder transducers. This is done totally flat, which also means you get to have more immediacy from the sound and not run EQs on it: just balance the microphone types. If you are running piezo and speaker into a single input like I am, then you can only adjust their balance by moving the speaker nearer or farther away from the drum head, but that works quite well. It’s good for a ‘fixed drum setup’ where your studio drums are set up and left ready to go: finetune the positioning as you get familiar with how it works, and use the normal mic (doesn’t have to be a 57, but I like my SM57 in this role as midrange mic) to fill in the normal kick drum sound.

I’ve got an internal damping system in there: Evans kick dampers upside-down, with the corners of the pads screwed to lug bolts, and the part that’s normally along the floor of the drum, suspended in the air not really touching either head. This is to substantially damp low frequency ring while leaving the heads able to ring at higher frequencies: but they’re loose, so those higher frequencies are mostly ‘papery’ color, not basketball-bounce color from tight heads. This affects the real mic a whole lot, and you can hear it when that mic is soloed, but it doesn’t affect the piezo or speaker nearly as much. Exception: if your drum booms in the lows, the speaker/subkick ought to pick that up a whole bunch.

The great thing about the piezo and speaker ‘mics’ is this: these put out such a hot signal that they’re plugged directly into my MOTU 16A. If your mic pres are not exactly top of the line stuff, using this technique you can bring more thump AND more click to your drum recordings and not need more pres! Mic pres are maybe the hardest thing to do on a budget, and this lets you supplement your sound while running directly into cheaper line inputs, with good noise performance compared to mic pres. You could even get respectable recordings using just stereo overheads, and reinforcing those with the piezo and subkick mics run into line inputs, which might be a great way to get started on a budget interface that only has two built-in mic pres. I’ve tried this and it’s a neat sound with a lot of character and a very hyped, big kick drum sound (since all the direct sound is either subs or click, and all the ambient sound is the kick’s room sound, it’s huge in scale).